Gemini Project

James McDivitt and Ed White inside the Gemini spacecraft
for a simulated launch at Cape Canaveral

The Gemini Project was the second human spaceflight program conducted by the United States. It consisted of a series of two unmanned and ten manned NASA missions launched between April 1964 and November 1966. Gemini, with its
two-seater capsule, built on the success of the Mercury
Project and paved the way for the Apollo
Project. Equipped with the Orbital Attitude Maneuvering System (OAMS)
to create a controlled orbital and reentry path, the Gemini craft were the
first fully maneuverable American manned spacecraft.

The first two Gemini missions were unmanned. Gemini 1 was to check compatibility
between the Gemini spacecraft and the Titan II launch vehicle (see Gemini-Titan
II) and no attempt was made to separate the two during their brief flight.
Gemini 2 was a suborbital test of the Gemini reentry system. There then
followed 10 successful manned missions.

Gemini missions

mission

launch

recovery

duration

orbits

crew

Gemini 1

Apr. 8, 1964

-

-

-

unmanned

Gemini 2

Jan. 19, 1965

-

-

-

unmanned

Gemini 3

Mar. 23, 1965

Mar. 23, 1965

4 hr 53 min

3

Grissom, Young

Gemini 4

Jun. 3, 1965

Jun. 7, 1965

4 days 2 hr

62

McDivitt, White

Gemini 5

Aug. 21, 1965

Aug. 29, 1965

8 days

120

Conrad, Cooper

Gemini 7

Dec. 4, 1965

Dec. 18, 1965

13 days 19 hr

206

Borman, Lovell

Gemini 6A

Dec. 15, 1965

Dec. 16, 1965

1 days 1 hr 52 min

16

Schirra, Stafford

Gemini 8

Mar. 16, 1966

Mar. 16, 1966

10 hr 41 min

7

Armstrong, Scott

Gemini 9A

Jun. 3, 1966

Jun. 6, 1966

3 days 0 hr 21 min

44

Cernan, Stafford

Gemini 10

Jul. 18, 1966

Jul. 21, 1966

2 days 22 hr 46 min

43

Collins, Young

Gemini 11

Sep. 12, 1966

Sep. 15, 1966

2 days 23 hr 17 min

44

Conrad, Gordon

Gemini 12

Nov. 11, 1966

Nov. 15, 1966

3 days 23 hr

59

Aldrin, Lovell

Gemini 3

Command pilot: Virgil Grissom
Pilot: John Young
Highlight: first American two-manned spaceflight

Young, in foreground, with Grissom inside the Gemini
3 capsule

The first manned Gemini and the first American space mission with two astronauts
aboard. During the flight, Gemini 3's orbit was varied using thrusters to
rehearse techniques needed for upcoming rendezvous and docking missions.

The capsule was unofficially dubbed "Molly Brown" after a survivor of the Titanic and in reference to the fact that Grissom's Mercury capsule
sank and was lost during his first spaceflight. Illicit cargo included a
corned beef sandwich reportedly from Wolfie's Restaurant in Cocoa Beach,
which was bought by Grissom, carried aboard by Young, and partly consumed
by Grissom during the flight. Young was authorized to eat specially prepared
food, and Grissom was supposed to have gone without. The possibility that
weightless crumbs from the sandwich might have compromised safety led NASA
managers to clamp down on what future astronauts could take into space.

Although one of the goals of the program was to achieve pinpoint recoveries,
Gemini 3 splashed down about 95km from its primary recovery vessel (a result
of Molly Brown having less lift than wind tunnel tests had predicted). Unlike
the Mercury capsules, which came down upright, the Gemini capsules were
designed to splash down on their sides. In the event, the force of the impact
hurled the astronauts against their respective windows, causing the faceplate
in Grissom's helmet to crack and that of Young's to be scarred.

Gemini 4

Ed White on the first U.S. spacewalk. Tethered to
the Gemini 4 capsule, White can be seen holding a compressed gas "zip
gun" for maneuvers in his right hand

Considered the first long-duration American spaceflight, this was also the
first mission to be directed from Mission Control at the Johnson Space Center
instead of the Mission Control Center at Cape
Canaveral. Gemini 4's goals were to evaluate the spacecraft and crew
during a lengthy stay in space, rendezvous with the spent Titan II second
stage, carry out the first American spacewalk, and continue testing the
Orbital Attitude Maneuvering System (OAMS).

The plan to fly in formation with the Titan second stage proved to be a
real learning experience in orbital dynamics. To catch something in Earth's
atmosphere involves simply moving as quickly as possible in a straight line
to the place where the object will be at the right time. When the astronauts
tried to fly toward the target, they got farther and farther away. The problem
is that adding speed also raises altitude, moving the spacecraft into a
higher orbit than its target. This paradoxically causes the faster-moving
spacecraft to slow down relative to the target because its orbital speed
increases with increasing distance from the center of gravity (Earth's center,
in this case). To catch up with an object ahead of you in orbit, NASA learned,
you must drop down and then rise up after you catch up, rather than speed
up. This was a crucial lesson for future rendezvous maneuvers. But, for
Gemini 4, it was learned too late and the rendezvous was called off with
half the onboard fuel used up. Gemini 4's tanks were only half the size
of later models, and the fuel can to be conserved for essential maneuvering
later in the mission.

White also took longer than expected to prepare for his spacewalk because
the hatch had jammed. However, just over four hours into the mission, the
hatch was opened. White stood upright in his seat, fixed a 16mm camera to
the spacecraft to record his historic feat, and prepared to exit. On his
way out, he lost a thermal overglove, which he had elected not to wear and
which drifted away to become an unintended new satellite. White then propelled
himself away using a handheld maneuvering unit and became the first American
to walk in space. For the duration of his spacewalk, White remained tied
to the spacecraft by a 7.6m umbilical line that contained an oxygen supply
hose, bioinstrumentation wires, and a support tether. He reported that although
the line worked well as a retention device, it was awkward to use and easily
got tangled. After 20 minutes, McDivitt called his companion back inside
and White remarked, "It's the saddest moment of my life." White again had
to struggle with the latch and, during the five minutes he took to deploy
it, exceeded the cooling capacity of his spacesuit which led to severe condensation
inside the helmet; his heartbeat peaked at 180. Once again, the intended
landing point was missed by a wide margin – Gemini 4 splashing down
724km east of Cape Canaveral and some 80km off target.

Gemini 5

Gemini 5 crew, Pete Conrad and Gordon Cooper on their
way to the launch pad

A mission during which a new space endurance record was set and the United
States (temporarily) took the lead in total space man-hours. Gemini 5 showed
that astronauts could endure weightlessness for roughly the time needed
to fly to the Moon and back.

The spacecraft was supposed to meet up with a rendezvous evaluation pod
released early in the flight, but the rendezvous had to be canceled because
of problems with the Gemini 5 fuel-cell system – the first time such
a system had been using for supplying water and electricity in space. Instead
the crew performed a simulated rendezvous, worked out by Buzz Aldrin, with
a phantom target.

A number of other planned on-orbit maneuvering experiments were also called
off because of erratic behavior by the OAMS. These cancellations led to
plenty of idle time for the astronauts and Conrad later remarked that he
wished he had "brought along a book."

On the same day the capsule returned to Earth, Cooper, 160 km above the
Earth, spoke with fellow astronaut M. Scott Carpenter who, at the time, was 200 feet below the Pacific Ocean, in the Sealab II
habitat.

Once again, the splashdown was well off the mark, missing the target zone
by 143km – an error blamed on faulty data fed to the spacecraft by
ground computers.

Gemini 6A

A planned rendezvous between Gemini 6 and an unmanned Gemini Agena Target
Vehicle (GATV) had to be scrubbed when the GATV failed to reach orbit. Instead
a new mission, called Gemini 6A, was announced in which the capsule would
meet up with the manned Gemini 7 spacecraft. The latter was launched on
December 4, 1965, on a two-week mission but an attempt to launch Gemini 6A on
December 12 had to be called off when the Titan II first stage automatically
shut down one second after ignition. The shutdown was caused by an electrical
umbilical prematurely separating. But it was later found that, because of
a dust cap left accidentally in place on an engine component, the first
stage thrust was, in any case, in the process of decaying. Without the automatic
shutdown caused by the umbilical disconnect, the first stage decay might
have led to a catastrophic explosion. Schirra had the option of manually
ejecting from the capsule via rocket-powered ejection seats (unlike the
Mercury and Apollo launch vehicles, Gemini was not equipped with an escape
tower), but decided against this and the astronauts safely left the vehicle
after about 90 minutes.

Launch eventually took place three days later. A successful rendezvous was
completed just under six hours into the flight, the two spacecraft approaching
to within about 37m. Station-keeping maneuvers continued for over three
orbits at separation distances of 30-90m – close enough for the crews
to see each other. Gemini 6A then maneuvered away and the two spacecraft
flew in formation about 48km apart until Gemini 6A began its reentry sequence.
Achieving the most precise Gemini recovery to date, the capsule splashed
down just 11km from its primary target point.

Gemini
7

The longest Gemini flight; it rivaled even the Space
Shuttle in terms of length of stay in orbit for a single vehicle. Shortly
after the capsule separated from the Titan II second stage, the crew moved
to within about 18m of the spent booster and performed about 15 minutes
of station-keeping. The crew then prepared to carry out 20 experiments and
five OAMS tests, including an OAMS burn to place Gemini 7 on the right orbit
to serve as a rendezvous target for Gemini 6A. Rendezvous between the two
manned spacecraft – the first in spaceflight history – took
place on the eleventh day of the mission. (Vostok 3 and 4 passed within
6km of each other in August 1962 but this was not considered a rendezvous
because the capsules were not maneuverable.)

Gemini 7 was also the first American spaceflight during which for much of
the time the crew left off their pressurized suits. A new spacesuit was
introduced for the mission which, although lighter, proved uncomfortable
when worn for long periods. Both astronauts brought along books to read,
heeding the advice given by Conrad after Gemini 5. Gemini 7 splashed down
just 10km off target, barely beating the record set by Gemini 6A two days
earlier.

Gemini 8

The first successful dual launch and docking with a GATV and the world's
first on-orbit docking of two spacecraft. Originally scheduled for three
days, the mission was aborted after just one.

During the first six hours of the flight, Gemini 8 maneuvered nine times
in order to approach the GATV to within about 45m. Docking was achieved
just over half an hour later; however, a dangerous malfunction soon followed.
Just 27 minutes after docking, a short-circuit in the OAMS caused fuel to
be lost through one of the capsule's thrusters. Although the astronauts
didn't know exactly what was wrong, the effects were almost immediate. Seconds
after the mishap, the mated spacecraft began to spin rapidly. Armstrong
was able temporarily to correct the problem by sequentially firing the OAMS
thrusters, but the spin kept restarting. Mission controllers and the astronauts
assumed the problem was with the GATV, so promptly undocked; however, Gemini
8 began to spin faster – up to one revolution per second. The motion
so disoriented the astronauts that they had trouble seeing clearly, and
communications with the ground became difficult. Armstrong had to act fast
before the astronauts lost consciousness. In a rule-breaking move, he manually
disabled the OAMS thrusters, activated the Reentry Control System (RCS)
thrusters, and managed to steady the spacecraft's motion. But the process
used up so much RCS fuel that the rest of the mission had to be called off.

Gemini 8 returned safely to Earth in a designated emergency area of the
Pacific – the only Pacific splashdown of the Gemini program –
just 5km from the recovery ship. Not surprisingly, Armstrong and Scott suffered
severe space sickness, which continued after the capsule was recovered.

Gemini 9A

The Augmented Target Docking Adapter (ATDA) as seen
from Gemini 9 during one of their three rendezvous in space. The ATDA
and Gemini 9 spacecraft are 66.5ft. apart. Failure of the docking
adapter protective cover to fully separate on the ATDA prevented the
docking of the two spacecraft.

The prime crew for Gemini 9 had been Elliot M. See as command pilot and
Charles A. Bassett as pilot. However, these two astronauts were killed in
a T-38 jet training crash at St. Louis Municipal Airport, Missouri on February
28, 1966. Ironically, their plane bounced off the building in which the
Gemini 9 spacecraft was being prepared for flight, smashed into a parking
lot, and exploded – minutes before Stafford and Cernan touched down
at the same airport.

The original mission was to have involved docking with a GATV. However,
when the GATV failed to reach orbit NASA decided to launch an Augmented
Target Docking Adapter (ATDA) instead, and rename the mission Gemini 9A.
The ATDA was launched on June 1, 1966. Two days later Gemini 9A took off
and rendezvoused with the ATDA on the third orbit – only to find that
a docking would be impossible. The ATDA's shroud had only partially separated,
prompting Stafford and Cernan to label their target "the Angry Alligator."

Although docking was out of the question, the crew successfully completed
several test maneuvers, including a rendezvous using optical equipment only
and a rendezvous from above the ATDA rather than below as on previous flights.
These were important steps in flight-testing proposed docking techniques
between the Apollo Command and Lunar Modules.

Later in the mission, Cernan went on a spacewalk – the second of the
American space program-exiting the spacecraft manually without the help
from a maneuvering unit. He spent 1hr 46min. outside the capsule, tethered
by an umbilical line which he disparagingly nicknamed "the snake." During
the walk, Cernan was supposed to have carried out the first test of a thruster-powered
Astronaut Maneuvering Unit (AMU), stored in the Gemini 9A adapter section
and accessible only from outside the spacecraft. The AMU, which had a self-contained
life support unit, would have allowed Cernan to propel himself up to 45m
away from the spacecraft and back. However, he had to work so hard to prepare
and don the AMU that his helmet's faceplate fogged up and, worse, as he
struggled with the AMU, Cernan accidentally snagged an antenna on the capsule
which caused several tears in the outer layer of his spacesuit. The Sun
beating down on these rips caused hot spots and, together with the other
problems, led to the spacewalk being cut short and the AMU test abandoned.
Gemini 9A easily took the record for the most accurate splash-down of the
Gemini program – just 1.5km from its prime target.

Gemini 10

Command pilot: John Young
Pilot: Michael Collins
Highlights: docking, EVA, and two rendezvous

Gemini 10 successfully docked with the Agena Target
Vehicle. The Agena display panel is visible as is glow from Agena's
primary propulsion system

The second successful dual launch and docking with a GATV. The latter was
launched about 100 minutes ahead of Gemini 10. Six hours later the two vehicles
rendezvoused and docked; however, these maneuvers used up more OAMS fuel
than expected and forced a revision of the flight plan.

Several orbital and docking training maneuvers were canceled, and Gemini
10 remaining docked to the GATV for about 39 hours – longer than originally
scheduled. During this time, two milestones were passed. At a mission elapsed
time of 23hr 24min. the hatch was opened and Collins stood up in his seat
with his upper body extending outside – the first "standup spacewalk"
in American space history. Collins was able to photograph stars in ultraviolet
light, only possible outside Earth's atmosphere, and took 22 shots of the
southern Milky Way using a 70mm camera. Also while the two spacecraft were
mated, a series of firings of the GATV thrusters boosted the orbit of the
vehicles to a height of 765km – a record for manned altitude (broken
though on the next Gemini flight). The thrusters were then fired in a series
of six maneuvers to place the mated spacecraft on a path to intercept the
GATV used during the Gemini 8 mission.

Gemini 10 undocked from its own GATV and, about three hours later, rendezvoused,
but did not dock, with the Gemini 8 target. This was accomplished solely
through visual location because the Gemini 8 GATV could no longer had power
to run its radar-locating devices. Two days into the mission, Collins went
on a second spacewalk, this time tethered to the spacecraft by a life-support
umbilical. Using his Personal Propulsion Unit, he jetted himself toward
the Gemini 8 GATV, just three meters away, and removed two experiment packages,
including a micrometeorite impact detector. While retrieving these packages,
he accidentally set the GATV gyrating slightly, causing problems for Young
as he attempted to keep the two spacecraft close together. Using the Gemini
10 thrusters for this purpose caused the fuel to run low and the spacewalk
was cut short. During the spacewalk, Collins also let go of his camera which
drifted off into space to become another unplanned Earth satellite.

Gemini 11

A mission during which rendezvous and docking was achieved with a previously
launched GATV in less than one orbit – a key goal because this procedure
might become necessary during the upcoming Apollo program. Other highlights
included two spacewalks by Gordon, the setting of a new world space altitude
record of 1,368km, and the completion of the first fully automated reentry.

One day into the mission, Gordon went on his first spacewalk, remaining
tied to Gemini 11 by an umbilical while attempting to attach a 15m rope
tether from the GATV to a docking bar on Gemini 11. Although the spacewalk
had been scheduled to last 105 minutes, Gordon grew tired while struggling
to attach the tether, his helmet fogged up, and consequently he went back
inside after just 21 minutes.

At a mission elapsed time of 40hr 30min. the GATV multiple-start engine
thrusters were fired to raise the orbit of the mated spacecraft to a maximum
altitude of 1,372km for two orbits, setting a manned altitude record that
was not broken until Apollo 8 headed for
the Moon. The two high-altitude orbits were completed in 3hr 23min. after
which time the GATV thrusters were fired to return the mated spacecraft
to their normal orbital altitude.

At a mission elapsed time of 46hr 7min. the hatch was opened for Gordon
to begin a standup spacewalk, during which he took of photos and then managed
to fall asleep! After the hatch was closed, Gemini 11 was undocked from
the GATV and maneuvered to allow it and the tethered GATV to slowly rotate
around one another. Although movement of the tethered spacecraft was erratic
at first, the motion stabilized after about 20 minutes. Then rotation rate
was increased, and again the motion stabilized. It was a challenge for the
astronauts to keep the rope tether tight between the spacecraft –
it remained stiff, but moved somewhat like a jump-rope as the spacecraft
orbited one another. This motion between the spacecraft caused artificial
gravity to be created in space for the first time – even though it
was only 0.0015 that on Earth. Gemini 11's return to Earth marked the first
fully automatic splashdown of the American space program. After initial
retrorocket firing, computers made all of the necessary adjustments to bring
the capsule down about 5km from its target point.

Gemini
12

The final Gemini mission, during which the crew made the first observation
of a solar eclipse from space. After Gemini 12 had docked with its GATV,
Aldrin carried out the first of three spacewalks, attaching a 30m rope from
the GATV to a docking bar on the capsule – a tether twice as long
as that used on Gemini 11. To combat some of the problems of fatigue experienced
on previous spacewalks, a number of astronaut restraints had been fitted
to Gemini 12's exterior. These helped Aldrin work at a more methodical,
relaxed pace. His spacewalk was also the first to have been rehearsed underwater
in NASA's Neutral Buoyancy Tank. Gemini 12 splashed down less than 5 km
from its primary recovery target area.

Gemini Agena Target
Vehicle (GATV)

A modified Agena stage launched by an Atlas,
which served as a target for rendezvous and docking experiments during the
Gemini program. The GATV was an Agena D with a Target Docking Adapter (TDA)
on the front. At the start of the Gemini 9 mission, the GATV launch failed
and the vehicle fell into the ocean. It was replaced by a backup called
the Augmented Target Docking Adapter (ATDA) which was not a modified Agena
but simply a TDA with a cylindrical back end to mate it directly to the
Atlas. Unfortunately, the ATDA's shroud failed to separate properly leaving
it in "Angry Alligator" mode and unable to support the docking.